PHILADELPHIA (AP) — Transit workers went on strike early Tuesday in Philadelphia, shutting down bus, trolley and subways that provide about 900,000 rides a day and raising fears a prolonged walkout could keep some voters from the polls on Election Day.

A union representing about 4,700 workers went on strike at 12:01 a.m. Tuesday after being unable to reach a contract agreement with the Southeastern Pennsylvania Transportation Authority.

Some officials fear that if the strike is not ended by Election Day, some Philadelphia residents may have a hard time getting back and forth from work and also finding time to vote.

Businesses, hospitals and schools began preparing last week for a possible transit shutdown.

The strike will have a major impact on the Philadelphia school system though it will remain open. SEPTA provides rides for nearly 60,000 public, private and charter school students.